Provide more reporting options to SkyFunctions 

With more specific information to be reported by Skyfunctions, e.g.,
to inform the build-event protocol on missing files, the EventHandler
interface is no longer enough. Therefore, provide an enriched context
for reporting events.

--
Change-Id: I2d06166fe4d5b9054e24ad8c752fafc039e3f9f8
Reviewed-on: https://cr.bazel.build/8794
PiperOrigin-RevId: 148463437
MOS_MIGRATED_REVID=148463437
diff --git a/src/main/java/com/google/devtools/build/skyframe/WalkableGraph.java b/src/main/java/com/google/devtools/build/skyframe/WalkableGraph.java
index 8f3dd04..5b98079 100644
--- a/src/main/java/com/google/devtools/build/skyframe/WalkableGraph.java
+++ b/src/main/java/com/google/devtools/build/skyframe/WalkableGraph.java
@@ -14,7 +14,7 @@
 package com.google.devtools.build.skyframe;
 
 import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
-import com.google.devtools.build.lib.events.EventHandler;
+import com.google.devtools.build.lib.events.ExtendedEventHandler;
 import com.google.devtools.build.skyframe.QueryableGraph.Reason;
 import java.util.Collection;
 import java.util.Map;
@@ -99,7 +99,8 @@
   /** Provides a WalkableGraph on demand after preparing it. */
   interface WalkableGraphFactory {
     EvaluationResult<SkyValue> prepareAndGet(
-        SkyKey universeKey, int numThreads, EventHandler eventHandler) throws InterruptedException;
+        SkyKey universeKey, int numThreads, ExtendedEventHandler eventHandler)
+        throws InterruptedException;
 
     /**
      * Returns true if this instance has already been used to {@link #prepareAndGet} {@code